So what is a parenthetical expression?These are expressions, or phrases often found in the middle of a sentence, that disrupts the flow of thought. They do not deal directly with the topic in hand. They are usually offset by commas, parentheses and dashes.
The clauses that precede and follow a parenthetical expression can independently form a complete sentence without the parenthetical expression.
A parenthetical expression is not essential to a sentence.
Let's have a look at some examples:
The cat woke up early that morning, he had mice to catch.
He had mice to catch, the cat woke up early that morning.
A parenthetical phrase can appear at the end or beginning of a sentence.